Liquid detergent compositions

ABSTRACT

A PHASE-STABLE, HEAVY-DUTY, LIQUID DETERGENT EMULSION COMPOSITION COMPRISING A SYNTHETIC ORGANIC NONIONIC DETERGENT AND TRISODIUM NITRILOTRIACETATE IN AN AQUEOUS MEDIUM CONTAINING A TERNARY EMULSION STABILIZER SYSTEM WHICH IS A FIRST STABILIZER COMBINATION OF A HYDROLYZED LINEAR COPOLYMER OF ETHYLENE AND MALEIC ANHYDRIDE PLUS A HYDROLYZED CROSS-LINKED COPOLYMER OF ETHYLENE AND MALEIC ANHYDRIDE, A SECOND STABILIZER WHICH IS A HYDROTYPE AND A THIRD STABILIZER WHICH IS AN ELECTROLYTE.

United States Patent 3,574,122 LIQUID DETERGENT COMPOSITIONS ThomasAquinas Payne, Jr., Teaneck, and Warren Eric Olson, Verona, N.J., andSamuel Hirsch C0hcn,, Bronx, N.Y., assignors to Lever Brothers Company,New York,

No Drawing. Filed Aug. 18, 1967, Ser. No. 661,522

Int. Cl. Clld 1/12, 3/066 US. Cl. 252-137 5 Claims ABSTRACT OF THEDISCLGSURE A phase-stable, heavy-duty, liquid detergent emulsioncomposition comprising a synthetic organic nonionic detergent andtrisodium nitrilotriacetate in'an aqueous medium containing a ternaryemulsion stabilizer system which is a first stabilizer combination of ahydrolyzed linear copolymer of ethylene and maleic anhydride plus ahydrolyzed cross-linked copolymer of ethylene and maleic anhydride, asecond stabilizer which is a hydrotrope and a third stabilizer which isan electrolyte.

The present invention relates to phase-stable, heavyduty liquiddetergent emulsion compositions.

The public has shown considerable acceptance of liquid detergentformulations because of their convenient handling and measuring andbecause of their non-dusting characteristics. Unfortunately, whenformulating liquid, heavy-duty detergents containing a non-ionicdetergent active, it is difiicult to achieve homogeneity because of thesalting out effect of the added builder material, e.g., sodium orpotassium pyrophosphate. In the past this salting out efiect has beensolved to a great extent by the inclusion of binary stabilizer mixturescontaining (a) various resins (see co-pending US. patent applicationSer. No. 362,489, filed Apr. 24, 1964, and now abandoned) and (b) smallamounts of an organic hydrotrope such as sodium xylene sulfonate, sodiumtoluene, sulfonate and the like. The binary stabilizer systems of theprior art which are effective when using inorganic builders, such as thepyrophosphates, have been found unsuitable in producing stablehomogenous liquid detergents containing trisodium nitrilotriacetate (anorganic sequestrant) in place of most or all of the inorganic builders.To illustrate, if a liquid detergent containing all of the ingredientsset forth in the above-mentioned co-pending US. patent application areused with the exception that 25% trisodium nitrilotriacetate issubstituted in place of an equal amount of tetrapotassium pyrophosphate,a liquid is formed which readily separates into two phases upon standingor upon testing by the accelerated phase-stability test as set forthhereinafter. Homogenization of such mixtures does not alter the aboveresult.

It is, therefore, an object of the present invention to provideheavy-duty liquid detergent emulsion compositions containing a nonionicorganic detergent and trisodium nitrilotriacetate as an organicsequestrant builder, which emulsion will have phase stability. Anotherobject is to provide phase-stable, heavy-duty liquid detergent emulsioncompositions which are free from or substantially free from phosphatebuilders. A further object of the invention is to provide phase-stable,heavy duty liquid 3,574,122 Patented Apr. 6, 1971 detergent emulsioncompositions having improved detergency not only in hot water, but alsoin cold water. Other objects of the invention include the provision ofphase-stable, heavy-duty liquid detergent emulsion compositions whichhave improved mildness and lower toxicity, which are readily preparedand which can be produced as a reasonable cost.

The above objects and advantages of the present invention are obtainedby the provision of a phase-stable, heavyduty liquid detergent emulsioncomposition which contains water as the dispersion medium, a nonionicorganic detergent as the active detergent component, trisodiumnitrolotriacetate as an organic sequestrant builder and a ternarystabilizer system for maintaining the 'phase stability of the emulsion.The emulsion compositions of the invention further contemplate theinclusion therein of various compatible adjuvants.

As noted above, water serves as the continuous phase or dispersionmedium for the emulsion compositions. The amount of water present in thecomposition varies depending upon the concentration desired and hencewater will comprise the substantial balance of the compositions. Ingeneral, water will be present in the order of from about 40% to about60%, and usually from about 45% to about 55% by weight of thecomposition.

The synthetic organic nonionic detergent or mixtures thereof serve asthe detergent active material of the composition and are generallypresent therein in an amount from about 6% to 15% by weight, and moreusually are present in an amount from about 8% to about 10% by weight.The synthetic organic nonionic detergents are the well knownpolyoxyalkylene compounds which are formed by condensing several molesof an alkylene oxide, such as ethylene oxide or propylene oxide, with ahydrophobic base, such as alkyl phenols, long-chain aliphatic alcoholsand mercaptans, propylene oxide-propylene glycol condensates, etc.Representative examples of suitable nonionic detergents are listed inthe following tabulation:

Average ethylene oxide content, Trade name I-Iydrophobe moles Sterox DJDodecylphcnol 10 Sterox MJb.- n-Dodecylphenol 10 Triton X100 Octylphenol10 Igepal C0530 6 Igepal 00-630.- 9 Igepal CO730 15 Igepal RC-52 6Igepal RC-760 "do 11 Igepal DJ-SQO Dinonylphenol l Tall oil alcohol 9Adol 42-10EO Unhardened tallow alcoho1 10 Alfonic 1418-6. n-Cu-Cmalcohols 1 62. 5 Tergitol 15-8-15 n-On-Cn secondary alcohols 7. 5Tergitol 15-8-9 .do 9 N eodol 25'9"... Cit-C15 primary straight-chain 29 alcohols. Sterox All- Tridecyl alcohol l0 1 Percent.

When the expression straight chain is used herein and in the appendedclaims. it is intended to include the alcohols which are substantiallystraight chain, i.e., at least about 70% straight chain with theremainder branched chain.

Other suitable nonionic detergents include the polyoxyethylenepolyoxypropylene ethanols having the empirical formula HO(C H O),,(C HO) (C I-I O) H prepared by condensing ethylene oxide with a hydrophobicbase formed by the condensation of propylene oxide with propylene glycolwhere b is an integer from 26 to 30 and a plus is an integer such as themolecule contains from 0% to 10% ethylene oxide (Pluronic L-60) or from10% to 20% ethylene oxide (Pluronic L-61) or from 40% to 50% ethyleneoxide (Pluronic L-64).

The trisodium nitrilotriacetate serves as an organic sequestrant builderin order to impart heavy-duty (ability to clean soiled clothing)properties to the detergent com: positions. The trisodiumnitrilotriacetate is generally present in the compositions in an amountfrom about 15% to about 35% by weight and more usually it is present inan amount from about 20% to about 30% by Weight, because in this latterrange maximum detergency in both cold and hot Water is generallyobserved.

As noted above, the detergent emulsion compositions contain a ternarystabilizer system in order that the emulsions will be phase-stable uponprolonged storage. The first stabilizer of the ternary stabilizer systemis a combination of a hydrolyzed linear copolymer of ethylene and maleicanhydride plus a hydrolyzed cross-linked copolymer of ethylene andmaleic anhydride. Generally from about 0.6% to about 1.2% by weight, andmore usually from about 0.8% to about 1% by weight of the firststabilizer combination is used. The relative amounts of the linear andcross-linked copolymers may vary depending upon molecular weight, degreeof cross-linking and other factors, but usually the cross-linkedcopolymer is present in a greater amount than is the linear copolymer.These copolymers, as noted hereinafter, are added to the compositions intheir anhydride form and then hydrolyzed to their acid form. They existin the finished product either in the acid or salt form depending uponthe alkalinity of the finished product.

Suitable linear copolymers of ethylene and maleic anhydride areavailable from the Monsanto Company under the designations DX84021,DX840-3l BX-8404 118, etc. Cross-linked copolymers are available underthe designations DX-840-61, BX-84041, DX-84081, DX-840 9l and similarmaterials in this series. In general, the monomers are polymerized at1:1 ratio, the resin having molecular weights ranging from about 1500and upwards. The cross-linked copolymers are generally cross-linked witha diamine, an alkylene polyamine, or a diolefinic material such as anether or a hydrocarbon, etc. Examples of polyamine crosslinking agentsinclude diethylene triamine, triethylene tetramine, tetraethylenepentamine, and higher molecular weight polyethylene polyamines.Exemplary diolefinic cross-linking agents include divinyl benzene,diallyl ether, vinyl crotonate, diallyl esters, and the like. The linearand cross-linked copolymers which can be utilized in preparing thecompositions of the invention include the following:

I Determined on a 1% solution of the resin in dimethyl formamide at 25C.

Cross-linked resin: Viscosity in cps.

DX-840-6l 12,000 DX-840-71 40,000 DX84081 80,000 DX-840-91 160,000

llleasureinents made alt 25 C. on a 1% aqueous solution, adjusted to pH9 with ammonium hydroxide, using a Brookfield Viscometer, N0. 6 spindleat r.p.m.

The second stabilizer of the ternary stabilizer system is a hydrotropewhich serves to help solu'bilize the synthetic organic nonionicdetergent in the aqueous medium in spite of the presence therein of thetrisodium nitrilotriacetate. The hydrotrope is generally present in theemulsion compositions in an amount of from about 2% to about 8% byweight, and more usually it is present in an amount from about 4 toabout 6% by weight. Hydrotropes are Well-knwon materials and includemethyl Carbitol (diethylene glycol monomethyl ether), and the alkalimetal salts of short chain alkyl aryl sulfonates, such as sodium andpotassium xylene sulfonates, sodium and potassium toluene sulfonates,mixtures thereof, and the like.

The third stabilizer component of the ternary emulsion stabilizer systemis a strong or weak electrolyte. In view of the fact that electrolytesare known to salt out nonionic organic detergents from aqueous media, itis indeed quite unexpected that an electrolyte would serve as anemulsion stabilizer component for the ternary emulsion stabilizer systemused in the compositions of the invention. The electrolyte is generallypresent in the emulsion compositions of the invention in an amount fromabout 4% to about 15 by weight and more usually it is present in anamount from about 6% to about 10% by weight. The electrolyte can be aninorganic or an organic compound, typical suitable examples of whichinclude the alkali metal, e.g., sodium and potassium, silicates,sulfates, carbonate, pyrophosphates, chlorides and orthophosphates, andethylene diamine tetraacetic acid.

Since the ternary stabilizer system contains three components eachexerting its respective cooeprative influence as an emulsion stabilizer,and since the chemical nature of each of the component stabilizers canbe considerably varied, it will be appreciated that the above amounts ofstabilizer components are general ranges which have been found to beoperable. However, in view of the variable effectiveness of thestabilizer components, the above amounts thereof are adjusted, asnecessary, to maintain the emulsion composition in a phase-stable form.For example, as the amount of electrolyte is increased, the amount ofhydrotrope should also generally be increased.

In addition to the above-mentioned components, the phase-stable,heavy-duty liquid detergent emulsion compositions can contain variouscompatible adjuvants, as desired. For example, soil anti-redepositionagents, such as sodium carboxymethyl cellulose, can be included therein,generally in an amount up to about 1.0% by weight, although such agentstend to decrease phase stability. The compositions can further containthe well-known anionic and nonionic fluorescent dyes or opticalbrighteners which are usually present in a very small amount, such asabout 0.2% by weight. Regulators of pH, such as potassium hydroxide, canalso be included. The presence of potassium hydroxide is particularlydesirable when the electrolyte is a silicate in order to preventseparation of the silicate from the emulsion. Usually small amounts ofpH adjusters are employed, for example, up to about 1% by weight. Othercompatible adjuvants which may be included in the emulsion compositionsare perfumes, colorants, germicides, and the like, which are generallypresent in small amounts below about 0.5% by weight.

The phase-stable, heavy-duty liquid detergent emulsion compositions ofthe invention can be readily processed or prepared, provided certainpercautions are taken. Thus, the linear and cross-linked ethylene-maleicanhydride copolymeric stabilizer component in substantially anhydrousform must be rapidly dispersed in an aqueous solution in the presence ofthe synthetic organic nonionic surfactant and preferably also in thepresence of the hydrotropic stabilizer component. It is preferred thatthe copolymer be dispersed in an aqueous solution which already containsthe nonionic detergent. However, the copolymers and nonionic detergentcan be simultaneously dispersed in the aqueous solution, the mainrequirement being that the copolymers are hydrolyzed in the presence ofthe nonionic detegent. It is preferred that the aqueous solution be atan elevated temperature, for example, ISO-160 F., to acceleratehydration of the anhydride portion of the copolymers to the acid form.

A further precaution is that extraneous alkaline materials shouldgenerally not be present during the hydration of the copolymers. Thus,after hydrolysis the pH of the solution should be definitely on the acidside, for ex ample, a pH of about 2.5-3.2. A further precaution inregard to the copolymers is that they should be rapidly dispersed in theaqueous medium.

Another percaution in the preparation of the compositions of theinvention is that an alkali, such as potassium hydroxide, should beadded to the formulation before the addition of the electrolyte theretowhen the electrolyte comprises a silicate. An additional precaution isthat the finished formulaions should be homogenized, generally at atemperature ranging from room temperature to about 170 F. and at apressure of about 500-3000 pounds per square inch.

A suitable order of addition of the components is as follows: water;hydrotrope; nonionic detergent (containing any nonionic fluorescentdyes); linear and cross-linked copolymers of ethylene and maleicanhydride; trisodium nitrilotriacetate; electrolyte (preceded by analkali, such as potassium hydroxide, when the electrolyte comprises asilicate); any anionic fluorescent dyes; and any soil antiredepositionagents. The formulation is then homogenized.

The compositions are used in the conventional manner for liquidheavy-duty detergent products, e.g., about one-half cup thereof perwashing machine load.

The compositions set forth in Tables I and II below were prepared by theabove procedure and were then tested for phase stability by a severeaccelerated phase stability test. In the accelerated phase stabilitytest a sample of the detergent emulsion composition was placed in acentrifuge tube and the tube inserted into a centrifuge which was thenrotated for 30 minutes at 5,000 rpm. which is equivalent to acentrifugal force of about 5,000 g. The term phasestable as used in thespecification an claims means that by this severe accelerated phasestability test, the compositions showed a phase separation ormulti-layered appearance of only 20% or less. A phase separation of 20%or less by this test is equivalent to a shelf-life of about 6 months orlonger.

The detergent compositions set forth in Table I below are presented forcomparative purposes and do not constitute formulations falling withinthe scope of the invention. They do illustrate, however, the necessityfor the ternary stabilizer system and the requisite amounts ofstabilizer components since they all had a phase separation greater than20%.

TABLE I In comparative Example A in Table I above, there was neither ahydrotrope nor an electrolyte present and accordingly the compositionshowed a phase separation by the above test procedure of In comparativeExamples B and C, the compositions were free from any hydrotropecomponent and accordingly these compositions showed a phase separationof 40% each. Comparative Example D was free from an electrolyte andhence had a phase separation of 40%. Comparative Examples E, F and Gcontained the requisite components of the ternary stabilizer system butcontained an inadequate amount of hydrotrope component, namely, anamount thereof below about 2%, and hence these comparative compositionsshowed a phase separation ranging from a 35% to 45%. In comparativeExample H which contained the requisite ternary stabilizer systemcomponents, the amount of hydrotrope stabilizer component was in excessof the requisite maximum amount of about 8% and accordingly thiscomparative composition showed phase separation immediately afterpreparation and before centrifugation. The remaining comparativeExamples I and I also contained the requisite ternary stabilizer systerncomponents but contained an inadequate amount of the electrolyte,namely, an amount below about 4%, so that these compositions showed aphase separation of 29% and 30% respectively.

The compositions set forth in Table II below are representative of thephase-stable, heavy-duty, liquid detergent emulsion compositions of theinvention which contained the ternary stabilizer system in the requisiteamounts of stabilizer components.

It will be noted that all of the examples in Table II above werephase-stable by the above test procedure in that they showed a phaseseparation of only 20% or less, ranging to a remarkably low value ofonly 1.5% phase separation for Example 10. The examples in Table IIfurther illustrate representative variations in the essential andoptional components of the compositions of the invention and in thevarying amounts thereof which may be employed.

The compositions of the invention are not only phasestable as shown bythe data set forth in Table II above, but further tests thereon haveestablished that they possess remarkable detergency properties. In thisconnection detergency tests have shown that the representativeformulation of Example 8 is superior in both hot and cold waterdetergency to the leading granular detergent composition on the market.Thus, in cold water F.) and hot water (130 F.) having a hardness of 180p.p.m. the average detergency units for the cleansing of cotton/ Dacroncloth soiled with vacuum cleaner dirt were as follows: Example 8:232,leading granular detergent composition=19.4 (for cold water): andExample 8:

Example N0 Components:

Neodol 25-9 8 Trisodiurri nitrilotrlaeetate S9dium carboxymethylcellulose. Fluorescent dyes Potassium hydroxide- Water Percent phaseseparatiorL... Viscosity (cps) 0.' s Amount sufiicient to br 55 40 40 4I of s .I 0. 0.8

ng total of compositions to by weight 1 Phase separation afterpreparation;

9 sisting of sodium silicate and sodium sulfate, and the bal- OTHERREFERENCES ance substantially waterthe above amounts of the three i oAcid Chelatin 3 g Agents 1n Detergent Applicasiablhzer onents bemgadlutsed to mamtam the emul' tions, Pollard, Soap and ChemicalSpecialties, September slon composition phase-stable. 1966 pp 5862 and130435.

References Cited HERBERT B. GUYNN, Primary Examiner UNITED STATESPATENTS 3,346,504 10/1967 Herrmann 2s2 137 WILLIS Assistant Examiner3,346,873 7/1967 Herrmann 252-137 3,351,557 11/1967 Almstead et a1 252106 1 252--138, 152, 161 FOREIGN PATENTS 1,439,308 4/1966 France 252138

